1. Field of the Invention
This invention relates to a semiconductor light emitting device including a silver-containing metal film and a semiconductor light emitting apparatus including this semiconductor light emitting device.
2. Background Art
A semiconductor light emitting device having a light emitting layer on a substrate or other semiconductor layer is often configured so that light emitted from the light emitting layer is extracted from the semiconductor layer side. For example, in a flip-chip semiconductor light emitting device, the light emitting layer side of the device is in contact with the heat sink side, and light is extracted from the substrate side. Thus, high light extraction efficiency is compatible with high heat dissipation. On the other hand, the electrode of a semiconductor light emitting device is sometimes made of silver or a silver alloy. Silver efficiently reflects the light emitted from the light emitting layer, and hence is suitable to realize a semiconductor light emitting device with high brightness.
However, silver is susceptible to migration, oxidation, and sulfidation, and may result in the decrease of emission intensity, lifetime, and breakdown voltage, and insulation failure. Migration is accelerated by exposure to moisture and impurity ions contained in ambient air, dielectric film, and the treatment liquid used during the device processing, and by electric field concentration during energization.
To solve this problem, there is a proposal for protecting a silver electrode by covering it with a metal other than silver or a protection film to prevent migration and reduce degradation (see, e.g., JP-A 2006-245231 (Kokai) and JP-A 2003-168823 (Kokai)).